John Martin's Book was a children's magazine aimed at five- to eight-year-olds. Martin Gardner wrote that it was a "pioneering publication" and the "most entertaining magazine" aimed at this age group published in the US.[3]:145 Priced from 10 to 50 cents over its twenty-year run, it was primarily purchased by middle and upper income families due to its cost.[2][3]:145

"John Martin" was the pseudonym of Morgan van Roorbach Shepard (April 8, 1865–May 16, 1947).[4] He was born in Brooklyn, New York but raised on a plantation in Maryland and took his name from the colony of martins that lived there. His mother died when he was nine, a crushing blow, and he was sent to a series of boarding schools where he was frequently bullied. As an adult, he claimed he was caught up in a revolution in Central America. He ended up working a variety of jobs in California, including a streetcar conductor, where he was fired for giving free rides to children, a newspaper reporter, and a bank clerk. He opened a business designing greeting cards in the Crocker Building in San Francisco, California, but it was demolished by the 1906 San Francisco earthquake and his leg was badly injured while he was trying to retrieve items from his office safe.[3]:147–48

While recovering and bedridden he began writing children's stories and verse for publication. He began writing long, illustrated letters to children, which in 1908 became a small publication called John Martin's Letters he was mailing to 2000 children a month. In 1912, it became the magazine John Martin's Book.[2][3]:148–50

The magazine included stories, illustrations, and puzzles. John Martin's House also published a series of hardcover John Martin Big Books reprinting material from the magazine.[3]:158 The magazine's puzzles were presented by a character named Peter Puzzlemaker. A collection of these puzzles was published by John Martin's House as Peter Puzzlemaker in 1922 and republished by Martin Gardner in the 1990s.[3]:154